Cellulose precipitating agent



Patented Dec. 17, 1929 UNITED STATES PATENT OFFICE EMIL CZAPEK AND RICHARD WEINGAND, OF BOMLITZ, NEAR WALSRODE, GERMANY GELLULOSE PREGIPITATING AGENT No Drawingl Application filed August 31, 1926, Serial No. 132,900, and in Germany September 1, 1925.

This invention has reference to improvements in the precipitation of cellulose from its solutions by means of which a very strong and superior grade of an artificial fibrous material may be produced. In the manufacture of artificial silk from V1scose,,as heretofore practiced aqueous or acidified aqueous salt solutions have been employed as a rule. In accordance with our experiments it has been ascertained that a precipitating bath in which the Water is replaced by methanol presents great advantages over the precipitating baths heretofore known. Thus it has been found for example that aprecipitating bath consisting of a solution of magnesium chloride or magnesium-sulphate in methanol and an inorganic acid is particularly suitable. It is also possible within the scope of this invention to employ a mixture of methanol and aninorganic acid or merely a solution of an inorganic salt in methanol.

These precipitating baths among other important advantages are particularly distinguished from the baths heretofore known by the fact that they produce a'very rapid precipitation. Moreover, the threads produced in this manner immediately after their production possess a very reat tearing re sistan'ce owing to the dehy rating action of these baths, and are not liable to stick together, as it frequently occurs in the case of precipitating baths comprising aqueous solutions; and the finished threads are alsodistinguished' by'being comparatively highly 4 water-proof. It is also possible to manufacture threads of a high degree of fineness with these precipitating baths owing to the great tearing strength in the wet condition, and the threads may be easily washed without inury. In a modification the precipitation may he proceeded by a coagulation with substantially pure methanol.

We are aware that it has been suggested in United States Patent-No. 792,888 to em. ploy a mixture of methyl-alcohol with acetic 1. In the manufacture of artificial silk from viscose and similar cellulose solutions, the introduction of the cellulose solution in the formof threads into a precipitating bath containing, in non-aqueous solution in methanol, an inorganic precipitant soluble in methanol.

2. In the manufacture of artificial silk from viscose and similar cellulose solutions, the introduction of the cellulose solution in the form of threads into a precipitating bath containing, in non-aqueous solution with methanol, an inorganicsalt soluble in methanol.

In the manufacture of artificial silk from viscose and similar cellulose solutions by introducing the cellulose solutions in the form of threads into a precipitating bath, this bath containing, in non-aqueous solution with methanol an inorganic acid soluble in methanol.

4. In the manufacture of artificial silk from viscose and similar cellulose solutions, the introduction of the cellulose solution in the form ofthreads into a precipitating bath containing, in non-aqueous acidulated solution with methanol, an inorganic salt soluble in methanol.

-5. In the manufacture of artificial silk from viscose and similar cellulose solutions the introduction of the cellulose solution in the form of threads first into a bath of pure methanol and then into a bath containing, in non-aqueous solution with methanol, an inorganic precipitant soluble in methanol.

6. As a new article of manufacture artificial silk of very high tearing strength and 5 Waterproof qualities consisting of regenerated cellulose solidified by an inorganic precipifant with a non-aqueous solution of methano In testimony whereof We affix our signatures.

DR. EMIL CZAPEK. DIPL. ING- RICHARD WEINGAND. 

